The book shows how to make the rich information content of bi-temporal data available to business users, while simplifying the design, maintenance and retrieval of that data. Metadata declarations eliminate the need to directly model temporal data. Temporal data maintenance is isolated in code that can be invoked to update bi-temporal data in any database and from any application program, across the enterprise. Anyone who can write queries against conventional data will be able to write queries against the bi-temporal data structures described in this book.